The invention pertains to a process for decoding traffic information pertaining to a highway network transmitted by radio from a traffic control center to a terminal.
Traffic information which is transmitted by radio from a traffic information control center to terminals, which can be in, for example, motor vehicles, can consist of data on conditions such as the travel times, average speeds, etc., prevailing in individual segments (highways, parts of highways, lanes, parts of lanes of highways) of a highway network.
The segments of the part of the highway network to which the traffic information transmitted from the control center to the terminal pertains are usually identified in a set of traffic information by the use of segment-identifying segment data in the transmission which indicate status data representing a certain status (=event) and the segments affected by this status.
The task of the present invention is to optimize the traffic information in the most efficient and reliable and easiest to realize manner and thus to make it possible to reduce the volume of data transmitted.
The invention makes it possible to reduce the data volume of the traffic information to be transmitted from the traffic control center to the terminal. It is possible to achieve a significant a reduction in the volume of transmitted data by comparing:
segment information in the traffic information currently being received by the terminal is compared with
segment information represented in older traffic information previously received by the terminal, which information identifies the segments affected by the status data represented in the traffic information; and also by comparing
additional information indicating the travel direction of the affected segments (either additional travel direction information or implicit travel direction information contained in the sequence of transmitted segments or stored segments), the status information of the older traffic information being assigned to the segments of the current traffic information only when the comparison shows that agreement exists. Thus, for example, when, in older traffic information, the statement xe2x80x9ctraffic jamxe2x80x9d has been transmitted and stored as status information and, for example, two segments in a certain sequence have been transmitted and stored as segment information, it is possible for the new, current traffic information being sent by the control center to the terminal to contain only a segment chain which contains at least these two segments in the same sequence. Thus, even if the traffic jam has grown larger or smaller or has expanded at one end and become shorter at the other end, it is possible for the control center to transmit completely decodable traffic information with a smaller data volume simply by identifying the segments (or one segment and its travel direction), there being no need to repeat the specific status information. Instead of a comparison establishing the agreement of only two segments, a comparison establishing the agreement of three, four, five, or more than five segments in the terminal can also be used as the condition for concluding that the status data of the older traffic information also pertain to the segments of the current traffic information. By establishing a uniform set of definition rules in the control center and in the terminal, it becomes possible to create a transmission protocol associated with a reduced volume of data. The uniformity between the control center and the terminal should pertain to the type of agreement required; the set of uniform rules should state in particular whether at least two (or at least three, see above) segments must be in agreement or whether there must be one segment (or two or three or more than three) in agreement plus agreement with respect to additionally transmitted directional information pertaining to the travel direction (or directional information implicit in the travel direction-specific segment number).
The process for decoding can be realized in the terminal either as an electronic circuit, for example, or as a program. It is neither defined nor limited, however, by embodiment as a program.